Can I input from 2 separate devices through Firewire?

hey guys

So i have an MR816x and run 1 firewire connection into my desktop, using the interface with that PC for web, gaming, movies.

and then i have my macbook pro plugged in to the other firewire with my studio stuff on it.

my question is, if both are on, can the MR816 only pick up 1 at a time and just decide its self which one is the master its going to use?

is there a way to have both computers plugged in and working at the same time or switching between the two easily?

Cheers for any help with this, i didnt understand why it had 2 inputs if they dont both work!